1. Field of the Invention
The present invention relates generally to the attachment of wires, cables or other conduits to flexible structures, or between multiple structures expected to exhibit relative motion therebetween, and, more particularly, to the employment of such wires, cables or conduits in high strain-inducing environments while protecting the wires, cables or conduits from such strain and while also providing protection from dynamic or other natural and induced environments.
2. State of the Art
Wires, cables and other conduits, referred to collectively herein as transmission lines, are conventionally used to transmit power or signals in various applications. Such transmission lines may transmit power or signals, for example, electrically, hydraulically or pneumatically. Often such transmission lines are attached to an associated structure for which the transmission lines are carrying power or are communicating signals. For example, transmission lines are conventionally found in, and are in some manner attached to, buildings, cars, transport vehicles, railway cars, aerospace vehicles and numerous other structures to deliver power to, or communicate with, various components of such structures.
In numerous applications, the structure to which the transmission lines are attached may experience forces or motions which place a strain on the transmission lines. Alternatively, the transmission lines may be coupled between multiple structures, or between multiple components of a single structure, wherein the relative movement between the multiple structures may induce strain therein.
For example, transmission lines are conventionally attached to a rocket motor's casing for powering and controlling components associated with the rocket motor. A conventional rocket motor may include a casing fabricated from a composite material formed of fibers or filaments and a bonding agent and which is configured to accommodate a relatively large amount of strain during operation of the rocket motor. For example, operational stresses applied to the casing of a conventional rocket motor may result in a strain exhibited as an elongation of the casing of up to 2%. Additionally, pressure from within the rocket motor may cause a radial deformation of the casing. Transmission lines conventionally attached to such a casing may experience mechanical degradation and potential failure when exposed to high-strain magnitudes.
In an effort to reduce the strain experienced by transmission lines in such service, various techniques and systems have been employed. However, such conventional techniques and systems are expensive and require an extensive amount of time and labor to install. For example, a given rocket motor may require upwards of 2,500 individual parts, including various brackets, clamps and covers, to install the requisite raceways which house transmission lines associated with the rocket motor. Additionally, installation of such a raceway system may require several weeks of intensive labor.
Referring to FIG. 1, a cross-section of such a prior art raceway 100, coupled to a rocket motor 102, is shown. The raceway 100 is configured to house multiple transmission lines 104, which transmission lines may include various configurations and sizes of wires, cables and conduits. The transmission lines 104 may even include destruct charges 104A which are configured to destroy the rocket motor 102 in the case of an errant rocket path, as will be appreciated by those of ordinary skill in the art.
Clamping mechanisms 106 may be employed to bundle multiple transmission lines 104 together. The transmission lines 104 and/or the clamping mechanisms 106 may be coupled to various brackets 108, which may in turn be attached to the casing 110 of the rocket motor 102 by means of fasteners or through use of an adhesive. Covers 112 of various configurations serve to conceal and protect the transmission lines 104 from an external atmosphere and provide a more aerodynamic profile on the rocket motor exterior.
Numerous design requirements must be met in implementing the raceway 100 with the rocket motor 102. For example, each bracket 108 may need to be individually tested upon assembly. Any adhesive or shear ply used in the installation of the raceway 100 must be able to withstand local elongation transferred from the rocket motor 102. Further, the raceway covers 112 must be designed to slide relative to other components during operation of the rocket motor 102 so as to prevent mechanical damage to themselves or other components of the raceway 100. For example, slots may be formed in the covers 112, allowing fasteners to be placed therethrough, thereby maintaining the cover in a substantially fixed radial position relative to the rocket motor 102, but allowing the covers 112 a limited amount of longitudinal movement relative to the rocket motor 102, the brackets 108 and other components attached thereto.
Additionally, the raceway 100 must meet pressure and thermal design criteria. For example, the raceway 100 must be able to withstand both internal and external pressures which may result in a differential pressure of up to 10 pounds per square inch, or higher. In order to prevent thermal degradation, all covers may include a cork thermal protection which is conventionally manually applied. Further, a room temperature vulcanizing (RTV) sealant is conventionally applied along all edges during assembly. Also, air flow and temperature within the raceway 100 must be considered as it is often desirable to limit the exposure of the transmission lines 104 to hot air or other gases which may be present within the raceway 100.
Thus, as can be seen, a great deal of design, preparation, manufacture and assembly work goes into installing transmission lines on a rocket motor to ensure proper operation.
As mentioned above, installation of transmission lines on or between other structures may experience similar difficulties. For example, relative movement between a truck and a trailer (or between two railway cars) may induce unwanted strain in transmission lines coupled therebetween. Additionally, pressurized pipelines, rotating or moving aircraft surfaces and earthquake-proof buildings, to name a few examples, may induce unwanted strains in transmission lines associated therewith and extending between mutually movable components, or components which elongate in various directions under applied stresses.
In view of the shortcomings in the art, it would be advantageous to provide a device and a method for attaching transmission lines to or between structures and which allow the structure to experience relatively high strains, including strains induced by stretching, compression, or other flexure, while maintaining the associated transmission lines in a low-strain environment. Such a device and method might also desirably provide thermal and environmental protection to the transmission lines.
It would be additionally advantageous to provide a device and a method for controlling the strain experienced by transmission lines which is simple and relatively inexpensive to fabricate and install and/or implement. It would also be advantageous to provide such a device and a method which is easily tailored to specific applications and installations.